The term zeaxanthin as used in this specification means (3RS,3'RS)-zeaxanthin.
Rhodoxanthin is a naturally occurring carotenoid which can be used, inter alia, as a foodstuff coloring substance. Zeaxanthin, the (3R,3'R) antipode of which occurs in nature, can also be used as a foodstuff coloring substance (e.g. for egg yolk pigmentation).
Hitherto known synthesis for the manufacture of these two carotenoids, i.e. rhodoxanthin and zeaxanthin, require about 10 to 18 steps. By means of the process provided by the present invention, these substances can now be manufactured in a substantially simpler manner.